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Mini Shell
Mini Shell
#!/bin/sh
#
# Copyright © 2020 Helmut Grohne <helmut@subdivi.de>
# Copyright © 2020 Guillem Jover <guillem@debian.org>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
set -e
PROGNAME=$(basename "$0")
version="1.21.1"
EOL="\n"
PKGDATADIR_DEFAULT='/usr/share/dpkg'
PKGDATADIR="${DPKG_DATADIR:-$PKGDATADIR_DEFAULT}"
# shellcheck source=scripts/sh/dpkg-error.sh
. "$PKGDATADIR/sh/dpkg-error.sh"
show_version()
{
cat <<END
Debian $PROGNAME version $version.
This is free software; see the GNU General Public License version 2 or
later for copying conditions. There is NO warranty.
END
}
show_usage()
{
cat <<END
Usage: $PROGNAME [<option>...] <pathname>
Options:
-z, --zero end output line with NUL, not newline.
--instdir <directory> set the root directory.
--root <directory> set the root directory.
--version show the version.
-?, --help show this help message.
END
}
canonicalize() {
local src="$1"
local root="$DPKG_ROOT"
local loop=0
local result="$root"
local dst
# Check whether the path is relative and make it absolute otherwise.
if [ "$src" = "${src#/}" ]; then
src="$(pwd)/$src"
src="${src#"$root"}"
fi
# Remove prefixed slashes.
while [ "$src" != "${src#/}" ]; do
src=${src#/}
done
while [ -n "$src" ]; do
# Get the first directory component.
prefix=${src%%/*}
# Remove the first directory component from src.
src=${src#"$prefix"}
# Remove prefixed slashes.
while [ "$src" != "${src#/}" ]; do
src=${src#/}
done
# Resolve the first directory component.
if [ "$prefix" = . ]; then
# Ignore, stay at the same directory.
:
elif [ "$prefix" = .. ]; then
# Go up one directory.
result=${result%/*}
if [ -n "$root" ] && [ "${result#"$root"}" = "$result" ]; then
result="$root"
fi
elif [ -h "$result/$prefix" ]; then
loop=$((loop + 1))
if [ "$loop" -gt 25 ]; then
error "too many levels of symbolic links"
fi
# Resolve the symlink within $result.
dst=$(readlink "$result/$prefix")
case "$dst" in
/*)
# Absolute pathname, reset result back to $root.
result=$root
src="$dst${src:+/$src}"
# Remove prefixed slashes.
while [ "$src" != "${src#/}" ]; do
src=${src#/}
done
;;
*)
# Relative pathname.
src="$dst${src:+/$src}"
;;
esac
else
# Otherwise append the prefix.
result="$result/$prefix"
fi
done
# We are done, print the resolved pathname, w/o $root.
result="${result#"$root"}"
printf "%s$EOL" "${result:-/}"
}
setup_colors
DPKG_ROOT="${DPKG_ROOT:-}"
export DPKG_ROOT
while [ $# -ne 0 ]; do
case "$1" in
-z|--zero)
EOL="\0"
;;
--instdir|--root)
shift
DPKG_ROOT=$1
;;
--instdir=*)
DPKG_ROOT="${1#--instdir=}"
;;
--root=*)
DPKG_ROOT="${1#--root=}"
;;
--version)
show_version
exit 0
;;
--help|-\?)
show_usage
exit 0
;;
--)
shift
pathname="$1"
;;
-*)
badusage "unknown option: $1"
;;
*)
pathname="$1"
;;
esac
shift
done
# Normalize root directory.
DPKG_ROOT="${DPKG_ROOT:+$(realpath "$DPKG_ROOT")}"
# Remove default root dir.
if [ "$DPKG_ROOT" = "/" ]; then
DPKG_ROOT=""
fi
[ -n "$pathname" ] || badusage "missing pathname"
if [ "${pathname#"$DPKG_ROOT"}" != "$pathname" ]; then
error "link '$pathname' includes root prefix '$DPKG_ROOT'"
fi
canonicalize "$pathname"
exit 0
Zerion Mini Shell 1.0